In automobiles, the number of revolutions of a propeller shaft such as the output shaft of a transmission thereof is integrated (counted) and stored as odometric data by a total odometer and a trip odometer, the latter being disposed as may be needed. A known total odometer or trip odometer is constructed of a mechanical counter which has a data display portion in the shape of a rotary drum.
Each of such mechanical total and trip odometers is comprised of comparatively large mechanical parts which are ordinarily disposed at the rear surface of the instrument panel. It is, therefore, difficult to make the instrument panel etc. small in size. On account of the comparatively large mechanical parts disposed at the rear surface of the instrument panel, arrangement of an instruction display portion cannot be easily varied. It is, consequently, difficult to condense the instruction display portion.